Sheave assembly



July 5, 1932- w. D. DAVIDSON 1,865,842

SHEAVE ASSEMBLY Filed Nov. 12, 1928 "illuminiIll W @n HTTMNEY Patented July 5, 1932` muren srA'rss rArsN'r ortica WILLIAM D. DAVIDSON, OF LOS'ANG-ELES, CALIFORNIA, ASSIGNOR TO EMSCO DERRICK &

EQUIPMENT COBPAB'Y, OF LOS ANGELES, CALIFORNIA, A CORPORATION OF CALI- Formia SHEAVE ASSEMBLY Appneauon flied November 12, 192s. serial No. 318,681.

My invention relates to crown-blocks such as are employed in oil well equipment, and relates particularly to a novel Vsheave assembly for such crown-blocks.

In the oily producing industry a crownbloclr is installed at the top of the derrick above the well. A crown-block includes a number of sheaves over which cables are passed, `these cables being used at dierent times'. ln the ordinary crown-block the sheaves are mounted on shafts which are rotatably supported by bearings, these bearings in turn being supported by the I-beam l of the crown-block.

It is an object of this invention to provide a sheave assembly in whichthe sheave shaft is secured to the supporting beam and clamped against being rotated by means of the same structure.

A further object of the invention is to provide a combination of this character in which the shaft is held fromrotation, and the bearings or boxes, as they are called, are spaced apart by the same means. l

A still further object of the invention is to provide a combination of this character in which the shaft has recesses into which clamp straps extend. The recesses are at an angley to the axis of the shaft so that not only is the shaft restrained from rotation relative to the boxes, but the boxes are prevented from moving longitudinally on the shaft. Y

During installation or adjustment of the sheaves of the crown-block, workmen are usually busy on the derrick floor below. `If any parts ofthe crown-block are dropped, a serious accident is liable to occur. It is an object of this invention to provide a sheave assembly consisting of boxes and a shaft in which the parts are-all locked together so that the unit may Abe elevated to the crown-block and so that the assembly may be adjusted on vention is illustrated,

Fig. 1 is a Vfragmentary elevational view showingra crown-blockat the upper end of the derrick, and embodying the features of this invention.

Fig. 2 is an enlarged section of the-invention takenon the line 2-2 of Fig. 1.

Fig. 3 is a section taken on the line 3-3 of Fig. 2.

Referring to the drawing in detail, the numeral 11 represents the upper end of the derrick to which a crown-block 12 is secured. The crown-block 12 is provided with a number of parallel extending I-beams 14. Shaft assemblies indicated by the numeral 15 `and embodying the features of this invention are supported 'by the I-bea-ms 14. As shown best in Figs. 2 and 3, the sheave assemblies include a pair of boxes 16 having lower` faces 17 which rest on theupper flanges K which extend through the upper flanges ofA the I-beams and through lugs 2O provided at the opposite edges'of the boxes 16, as best illustrated in Fig. 3. The boxes 16 have openings 21 formed horizontally therethrough and at right angles to the direction of extension of the I-beams 141. The inner parts of the boxes 16 are provided with integral bridge portions 22 which form upper walls for the openings 21. The outer ends of the boxes 16vdo not have bridge-portions 22, and therefor-e the outer ends of the openings 21 ar-e only partly cylindrical so that the upper portions are exposed to the exterior. The inner ends of the openings 21, however, are closed by the integral bridge portions 22.

Adaptedto be supported by the pairs of boxes 16 isa shaft 24, the ends of which rest in the openings 21. The portion of the shaft 24C which rests in the outer parts of the openings 21 and the boxes 16 where the upper parts are cut away, are pro-vided with recesses 25 having iiat bottom faces 26 which are adapted to extend substantially horizontally Adapted to extend through the recesses 25 and to engage the flat faces 26 are clamp straps 27. The opposite ends ofthe clamp straps 27, as shown best in Fig. 3, have openings 28` formed therethrough so that bolts boxes.

29 may be extended through the ends of the clamp straps 27. These bolts 29 extend through openings 30 of the boxes 16 and heads 31 rest in enlargements 32 formed near the lower parts of the Nuts 34 are screwed onto the upper ends of the bolts 29, thus securing the clamp straps 27 to the boxes 16 and furthermore locking the shaft 24 and the boxes 16 together.

The clamp means of the invention serves a dual purpose. In the first place, clamp straps 27 by engaging the flat faces 26 prevent the shaft 24 from rotating relative to the boxes 16. In the second place, the clamp straps by virtue of their resting in the recesses 25, which recesses have opposing vertical walls 60 and 61, hold the boxes properly spaced on the shaft 24 so that they can not move too close together, and can not move from the outer ends of the shaft 24.

The shaft 24 is provided with a central hardened race portion 35. Surrounding the race portion 35 is a bearing 36. The bearing 36 in the form of the invention shown in the drawing is provided in the form of a roller bearing. Adapted to rotate on the shaft 24 is a sheave 37. The sheave 37 surrounds the race portion 35 of the shaft 24 and has a race opening 38 in which the bearing 36 is located. Side plates or thrust plates 39 are placedon opposite sides of the sheave 37 between the edges thereof and the inner edges of the boxes 16.

From the description and drawing it will be seen that by virtue of the integral bridge portion 22 the boxes 16 are provided with completely annular bearing faces 41 which are positioned on each side of the hub of the sheave 37. The side thrusts of the hub of the sheave against the boxes 16 are sometimes very heavy, and it is therefore desirable to provide large solid faces to receive this thrust. The provision of the integral bridge portions 22 accomplishes this result and provides a sheave assembly which is very rigid and has a bearing surface which is ample to withstand any of the enormous side thrusts to which it is subjected.

From the foregoing description it will be seen that the essential features of the invention reside first in the clamping means which restrains the shaft 24 from rotation and which spaces the boxes 16 on the shaft 24. The clamp means prevents the boxes from being moved too close together so that Jthere is insufcient room for the sheave 37 to operate properly between the boxes. rlhe outer walls of the recesses 25 prevent the boxes from moving between the ends of the shaft 24 and thus prevent their being disconnectedV from the assembly and falling to the floor of the derriclr. Another advantage, and important feature of the invention, resides in the completely annular bearing faces 41 which are provided as a result of making the bridge portions 22 integral with the main portion of each box.

In the drawing certain details of construetion have been shown, merely because these details render a more superior sheave assembly. It should be understood that the details of construction which do not affect the invention or change the principle thereof may be redesigned or eliminated without departing from the spirit and scope of the invention.

I claim as my invention:

1. In combination: a shaft; a box adapted to receive and support a portion of said shaft; a clamp bar adapted to extend through a recess formed in said shaft, said recess having a bottom wall and a side wall engageable by said clamp bar; and separate bolt means for securing said clamp bar to said box and for causing said clamp bar to grip said bottom wall of said recess.

2. In combination: a shaft; a box adaptedY to receive and support a portion of said shaft; a clamp bar adapted to extend through a recess formed in said shaft, said recess having a bottom wall and a pair of side walls engageable by said clamp bar; and separate bolt means for securing said clamp bar to said box and for causing said clamp bar to grip said bottom wall of said recess.

3. In a crown-block, the combination of: a complete unit preassembled in operative condition and including a shaft, opposed box members engaging opposite end portions of said shaft, a sheave journaled on said shaft between said box members, and clamp means associated with and rigidly clamping each box member to said shaft for preventing relative rotation of said shaft and said box members and for preventing relative displacement of the parts comprising said unit; a frame for supporting said unit; and other clamp means for rigidly clamping said box members to said frame, said other clamp means being entirely independent of said first named clamp means so that the latter may be operative while said unit remains in its preassembled condition.

4. A combination as defined in claim 3 in l which each box member provides an unbroken annular thrust surface adjacent said sheave.

i iro 5. A combination as defined in claim 3 in which each end portion ofsaid shaft is provided with a recess `and said box members are provided with openings adjacent the respective recesses, and in which the first named clamp means engage in said recesses through said openings.

In testimony whereof, I have hereunto set my hand at Los Angeles, California, this 3rd day of November, 1928. 

